Chemical Bonding

Chemical Bonding

Presenter: Dr. Luis Bello

​Chemical bonding refers to the forces that hold atoms together in a molecule or compound.

Atoms combine with each other to form molecules because of the attractive forces between their nuclei and electrons.

​There are three main types of chemical bonds:

ionic bonds, covalent bonds, and metallic bonds.

​Ionic bonding occurs when one or more electrons are transferred from one atom to another, resulting in ions with opposite charges that attract each other. For example, sodium (Na) has one valence electron, while chlorine (Cl) has seven.

When sodium and chlorine react, sodium donates its valence electron to chlorine, resulting in a positively charged sodium ion (Na+) and a negatively charged chloride ion (Cl-).

The electrostatic attraction between the oppositely charged ions forms an ionic bond, as in the compound sodium chloride (NaCl).

​​Ionic bonding

Multiple Choice

This image shows the bonding between Lithium and Fluorine. What does the red arrow show?

• electrons being shared

• electrons being transferred to Fluorine

• electrons being transferred to Lithium

• electrons being destroyed

Multiple Choice

Which of the following is NOT a step in forming an ionic bond?

• One atom shares its electrons with another one

• Opposite charged ions form due to the transfer of electrons

• One atom gives electrons to another one

• Oppositely charged ions attract

Multiple Select

An ionic bond is the attraction between: (Select ALL that apply)

• oppositely charged ions

• similarly charged ions

• metals and nonmetals

• neutral atoms

• cations and anions

Multiple Select

Which of the following could NOT form an ionic compound? Check all that apply.

• Li⁺ and Cl^-

• F^- and O^2-

• Ba²⁺ and Ag⁺

• Mg²⁺ and S^2-

Multiple Select

Which of the following could form an ionic compound? Check all that apply.

• Na⁺ and F^-

• S^2- and O^2-

• Ca²⁺ and Fe³⁺

• Mg²⁺ and Cl^-

​Covalent bonding occurs when atoms share electrons in order to achieve a stable electron configuration.

This can occur between two atoms of the same element, such as in the diatomic molecule hydrogen gas (H2), where each hydrogen atom shares its single electron with the other. It can also occur between different elements, as in the compound water (H2O), where each hydrogen atom shares one of its electrons with the oxygen atom. In a covalent bond, the shared electrons are attracted to both nuclei, resulting in a strong bond.

Multiple Choice

A polar bond is one that

• Has an electronegativity difference greater than 0.7

• Has an electronegativity difference greater than 0.5

• Has an electronegativity difference less that 0.5

• Has an electronegativity difference less than 0.7

Multiple Choice

Which of these would be covalently bonded

• Fr and K

• Sc and O 

• F and Cl

• He and Pt

Multiple Choice

How are covalent bonds explained?

• When one atom takes the other atom's electron

• When the atom shares an electron with an another atom

• When the two nucleus merge

• When the neutrons leave the nucleus

Multiple Choice

What two types of atoms make a covalent bond?

• 2 non-metals

• 1 metal and 1 non-metal

• 2 metals

​Metallic bonding occurs in metals, where the valence electrons are free to move throughout the entire metal lattice, rather than being confined to individual atoms.

This results in a "sea" of electrons that is attracted to the positively charged metal ions.

This attraction results in a strong metallic bond, which gives metals their characteristic properties such as high conductivity and malleability.

Multiple Choice

Metallic bonds form because metals

• "want" to give up valence electrons

• always share valence electrons

• have many valence electrons

• always gain valence electrons

Multiple Choice

In metallic bonds, the force of attraction is between

• positive and negative ions

• cations and electrons

• two different metals

• neutrons and electrons

Multiple Select

Metals are used to make electric wires because metals (choose all that apply)

• are ductile

• are shiny

• have free moving electrons

• form a lattice

Multiple Choice

Metals have positive ions in a ‘sea of electrons’. Which metal atom provides the most electrons for the sea?

• Aluminium

• Sodium

• Calcium

• Magnesium

Multiple Choice

Which statement describes the structure of copper?

• It has a lattice of negative ions in a ‘sea of electrons’.

• It has a lattice of negative ions in a ‘sea of protons’.

• It has a lattice of positive ions in a ‘sea of electrons’.

• It has a lattice of positive ions in a ‘sea of protons’

Molecular Geometry

​Molecular geometry refers to the three-dimensional arrangement of atoms in a molecule.

It is determined by the number and type of atoms in a molecule, as well as the bonding and lone pair electrons around each atom.

​There are several different types of molecular geometries.

​Linear: In a linear geometry, two atoms are connected by a bond and are arranged in a straight line.

Examples include CO2 and BeCl2.

​Trigonal planar: In a trigonal planar geometry, three atoms are bonded in a flat triangle, with an angle of 120 degrees between them. For example, boron trifluoride (BF3) has a trigonal planar geometry.

​Tetrahedral: In a tetrahedral geometry, four atoms are bonded in a pyramid shape, with an angle of 109.5 degrees between them. For example, methane (CH4) has a tetrahedral geometry.

​Trigonal bipyramidal: In a trigonal bipyramidal geometry, five atoms are bonded in a shape that looks like two pyramids joined at their bases, with angles of 90 and 120 degrees between the atoms. For example, phosphorus pentachloride (PCl₅) has a trigonal bipyramidal geometry.

​Octahedral: In an octahedral geometry, six atoms are bonded in a shape that looks like two square pyramids joined at their bases, with angles of 90 degrees between the atoms. For example, sulfur hexafluoride (SF₆) has an octahedral geometry.

​Bent structure is a type of molecular geometry in which a molecule has a bent or V-shaped structure.

This geometry is typically observed in molecules with a central atom that has three or four electron pairs, including one or two lone pairs.

In a bent structure, the two bond angles between the central atom and the two adjacent atoms are less than 180 degrees, resulting in a bent or V-shaped appearance. The exact bond angle depends on the number of lone pairs present on the central atom.

​For example, water (H₂O) has a bent structure with a bond angle of approximately 104.5 degrees.

This is because oxygen, the central atom in water, has two lone pairs of electrons that repel the bonding pairs of electrons, causing the H-O-H bond angle to be less than 180 degrees.

​

Another example of a molecule with a bent structure is sulfur dioxide (SO₂), which has a bond angle of approximately 119 degrees.

In SO₂, sulfur has one lone pair of electrons that cause the SO₂ molecule to have a bent shape.

Multiple Choice

What geometry will this molecular structure have?: H₂S

• bent

• tetrahedral

• linear

• trigonal pyramidal

Multiple Choice

Choose the correct shape for this molecule:

• Trigonal planar

• Trigonal pyramidal

• Tetrahedral

• Linear

Multiple Choice

Choose the correct shape for this molecule:

• Trigonal planar

• Trigonal pyramidal

• Bent

• Linear

Multiple Choice

Choose the correct shape for this molecule:

• Bent

• Trigonal pyramidal

• Trigonal planar

• Linear

Multiple Choice

Choose the correct shape for this molecule:

• Trigonal planar

• Trigonal pyramidal

• Bent

• Tetrahedral

Multiple Choice

Choose the correct shape for this molecule:

• Tetrahedral

• Trigonal pyramidal

• Bent

• Trigonal planar

Multiple Choice

Choose the correct shape for this molecule:

• Bent

• Linear

• Tetrahedral

• Trigonal pyramidal